The aim of this study is to address issues in the policy and practice of teating hypertension, particularly "mild" hypertension, by extending analyses in the Hypertension Detection and Follow-up Program (HDFP). The HDFP grant is scheduled to end November 31, 1988. The analyses proposed here are those that the HDFP investigators will not have time to finish by the end of the grant. They address important issues which have arisen from the HDFP and other investigators. In 1973-1974, the HDFP carried out a population based screen of over 159,000 persons, ages 30-69 years, in 14 U.S. communities; 10,940 men and women, including both blacks and whites, were enrolled in the trail and followed for mortality and morbidity through 1979. Additional mortality follow-up through 1985 has extended mortality surveillance to 11 years. A number of issues of interest to medical scientist and clinicians will be addressed by analyses of the extensive HDFP data base and by and extension or mortality surveillance to 15 years. Hypertension remains one of the most common adult chronic diseases, affecting perhaps 35 million Americans. Though data from both observational and experimental studies support the view that mild hypertension is a very significant part of the public health problem of high blood pressure, the issue of how to treat mild- hypertension remains controversial. It is not an inconsequential controversy. Before deciding whether to treat patients with mild hypertension, perhaps for the rest of their lives, a clinician must weigh the largely unknown risks associated with long-term exposure to antihypertensive drug therapy against the risk associated with long-term exposure to high blood pressure. The potential benefit of antihypertensive drug treatment when both mortality and morbidity are considered will be examined in HDFP hypertensive participants. Evidence of long-term, adverse effects of this treatment will be studied. Factors which were predictive of cardiovascular endpoints or which differentiated treatments response will be identified and studied both for their impact on treatment effects in various subgroups and for insights into approaches to treatment. These investigations can shed important light on the benefits and risks of treatment in individuals with various characteristics.